Conventionally, the develop of a luminaire has a purpose of faithfully reproducing an original color of a target object to be illuminated. Specifically, it is considered better as the colors of various target objects are seen closer to the colors seen under the standard light. This makes it possible to objectively evaluate a luminaire by using a general color rendering index.
However, the general color rendering index is not necessarily sufficient as an indicator for evaluating the appearance of characters written on a paper. Accordingly, as the indicator that quantitatively requires the white color sense of a paper from a correlation between the appearance of characters and the white color sense, there is used a chroma value acquired by using a calculation method by the CIE 1997 Interim Color Appearance Model (Simple Version). As for a luminaire for irradiating light with a chroma value controlled, there is known a luminaire using an LED light source irradiating light having a correlated color temperature of 5400 to 7000 K (see, e.g., Japanese Unexamined Patent Application Publication No. 2014-75186).
However, when the luminaire described above is used as a task lamp under a low color temperature environment, a user may feel a sense of discomfort due to the great difference of the correlated color temperature between task lamp light and ambient (environment) lamp light.